Induction furnace



N. R. DAVIS ETAL March l0, 1931.

INDUCTION FURNACE Filed sept.v 9, 192? INVENTRS Neville R.Davs and Cecil F? Burch BY m@ TTOs RNEY 4Patented Mar. 1,0, 1931 UNITED STATES PATENT OFFICE NEVILLE BYLAND DAVIS .AND CECIL BEGINALD BURCH, 0F MANCHESTER, ENGLAND, l ASSIGNORS T0 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A COR- PORATION OF PENNSYLVANIA INDUCTION FURNACE Application led September 9, 1927, -Serial No. 218,403, and in Great Britain November 3, 1926.

Our invention relates to furnaces and more particularly to electric furnaces of the induction type.

In electrical induction furnaces of the coreless type, employing, in general, a-helically wound inductor coil surrounding a metallic charge to bemelted, it is necessary to energize the coil at a relatively high current density which results in a considerable amount of heat being developed in the coil. To obviate this condition, it is necessary to resort to artificial cooling of the coil to prevent undesirable eilects thereupon.

The usual expedient has been to form the coil of iiattened tubing and to circulate a cooling fluid therethrough. The objection to such a construction is that the convolutions of the coil must be relatively large in crosssection to permit lthe passage therethrough of sufficient uid to effect the desired cooling thereof, and to provide sufficient metal to carry the relatively large electrical current necessary to effect the melting of the charge.

It is an object of our invention, therefore, to provide in an induction furnace, a, solid inductor coil and means formed upon a peripheral edge of the convolutions, of the coil` to effect the cooling thereof.

v In practicing our invention, we provide, in conjunction with a Crucible for containing the metal to be melted, a substantially helically-wound inductor coil surrounding the crucible, and means secured to the outer periphery of the coil convolutions for 'effecting the cooling thereof.

In the drawings,

Figure 1 is a vertical sectional view of an induction furnace embodying our invention,

Fig. 2 is a vertical sectional view of a convolution of the inductor coil shown in Fig. l,

Figs. 3 and 4 are vertical sectional views of modified forms of inductor coils.

Referring more particularly to Fig. 1, the furnace embodying our invention comprises a casing 2 of suitable heat-insulating material, a helically wound inductor coil 4 disposed therein and coaxial therewith, and a Crucible 6 surrounded by said coil and adapted to contain the material to be melted. An

The space between the casing, coil and i crucible is filled with a Suitable refractoryelectrically insulating material, such as air` conium silicate.

An annular plate 10 of refractory material is supported upon the upper peripheral faces of the casing 2 and crucible 6 to close the space therebetween occupied by' the inductor.

The discharge of molten material from the Crucible is facilitated by a passage formed through the plate 10 communicating with the Crucible and terminating in a pouring spout 12 formed on the outer periphery of the casing 2.

A suitable cover 14.-,v supported upon the plate 10, is adapted to be removed to permit the charging of material to be melted into the furnace.

`Since the particular form and construction of the furnace forms no part of the present invention, a more detailed description thereof is not deemed necessary.

In the preferred form, shown in detail in Fig. 2, the coil comprises a solid electrically conducting portion 20, rectangular in cross section, which is grooved along a peripheral edge thereof to receive a tube 22. constituting a conduit for a suitable cooling fluid.

The tube 22 is soldered or brazed in any ducting portion is grooved to form a relatively deep channel, and a fiat strip 24 is A soldered or brazed to the periphery thereof be melted, alternating current passing therethrough, especially at relatively high frequencies, is' confined almost entirely to that side of conductor 'which is nearest the axis of the coil. On the other hand, if the charge to be melted is located outside andaround the inductor, the current density Will be greatest in the portion of the inductor .Winding remote from the axis of the coil.

By the present invention, We have provided a cooling Huid conduit secured to the Winding or an inductor coil remote from the axis ont the coil which, in the present instance, is the point of lowest current density.

Quite obviously, the form of furnace shown, and the particular form of inductor coil are illustrative only and maybe changed considerably Without departing from the scope or' the invention. For example, if the furnace is designed sc that the charge surrounds the inductor the cooling fluid conduit will be secured to the inner periphery or the coil convolutions.

TVarious modifications may be made in our invention -Without departing from the spirit Vand scope thereof, and We desire therefore that only such limitations shall he placed thereon as are imposed by the prior art and setforth in the appended claims.

VIe claim as our invention:

l. In a coreless electric-induction furnace, a solid inductor coil adapted to surround the charge, to be melted, and means secured to said coil oregecting the artificial cooling thereof, said means comprising a metallic conduit, coextensive in length With a periphery or said coil.

2. In an induction furnace, an inductor coil ycomprising a solid helically Wound conductor, and means for cooling said conductor comprising a conduit coextensive in Alength 'with the outer periphery of said conductor and secured thereto in heat-exchanging relation.

3. An induction coil comprising a conductor rectangular in cross section having a groove in a periphery thereof, and means associated With said groove, said means acting to restrain a flow or" cooling medium to the periphery ci said conductor.

4. In an electric inductor furnace, an inductor characterized by a radially inner solid electrically-conducting portion and a hollow projectlng outer cooling portion adapted to receive a cooling liquid.

5. In an electric furnace, an edge-wound inductor of solid material and a watercooled coil outsideiof theinductor and having heat-conductive connection with the inductor. y

6. In an electric furnace, a primary winding, insulation between the conductors of the Winding forming with the Winding a pro-` 

